The present invention relates to a closed heat-decomposing appliance for the pretreatment on analyzing the components in a sample which may sometimes contain organics and a pretreatment method using it. In more detail, it relates to a closed heat-decomposing appliance for heat-decomposing organics and then absorbing the analyzed components into absorbing liquid on analyzing quantitatively or detecting the components in a sample which may sometimes contain organics by quantitative determination or detection, and a pretreatment method for heat-decomposing the sample and absorbing the testing components in sample using it. Moreover, it relates to a device automating the decomposition of sample, absorption of analyzed components and analysis, using the closed heat-decomposing appliance.
So far, for the analysis of components like halogen and sulfur in organics, usually pretreatment procedures of decomposing the organics under heat or combustion and absorbing the analyzed components has been done and then quantitative analysis has been performed by ion chromatography, titration, colorimetry, ion selective electrode method or the like. As the methods of this pretreatment, closed flask combustion method, combustion-tube method, sealed tube dry combustion method, hot-flask combustion method and vertical closed tube method are known.
Thereamong, the oxygen-flask method is described, for example, in “Yuki biryo teiryo bunseki” (Organic Quantitative Microanalysis) edited by “Yuki biryo teiryo kenkyuu kondankai” (Conversazione for Studying Organic Microanalysis), p. 383 (1969), Nankodo. Procedures are as follows: Namely, absorbing liquid is poured in a reaction vessel like Erlenmeyer flask, oxygen is filled up in the vessel, around several tens mg of sample is weighed, wrapped in filter paper being a combustion assistant, held between platinum meshes and fired, then this is inserted swiftly into the reaction vessel, which is turned upside down while securely pressing down the stopper and reaction vessel. During combustion of sample, the absorbing liquid blocks off the opening between flask and stopper, and, after combustion, the reaction vessel is shaken well to absorb the testing components into absorbing liquid. This oxygen-flask method requires no particular appliance to be prepared except reaction vessel, but has problems that the microanalysis is impossible due to contamination from filter paper that wraps the sample, a reaction vessel with size of an order of several hundreds ml must be used to secure the quantity of oxygen required for burning filter paper, thus requiring broad area for the space of experiment, that the skill is needed for the procedures such as firing the sample and burning it in the reaction vessel, and so on.
The combustion tube-burning method is described in detail, for example, by Honma et al in Analytical Chemistry, vol. 35, p. 536 (1986). Procedures are as follows: Namely, sample is inserted into a tube made of quartz or the like installed in a high-temperature furnace while flowing oxygen stream, and burned completely through catalyst, thereby gasfying the testing components to absorb into absorbing liquid. This combustion tube-burning method is suitable for the automation due to simple procedures, but, when ash content such as alkali metal is contained in the sample, it has drawbacks that the analyzed components transfer incompletely to absorbing liquid due to capture by ash content to make it difficult to perform accurate analysis, and the like.
The sealed tube-burning method is described in detail, for example, by Hozumi et al in Analytical Chemistry, vol. 38, p. 259 (1989). Procedures are as follows: Namely, overall sealed tube with the sample and oxygen sealed therein is inserted into a high-temperature furnace to heat and, after allowed to stand for cooling, the sealed portion is dropped into a vessel accommodated with absorbing liquid to break. Since the absorbing liquid enters forcibly into sealed tube due to negative pressure inside the sealed tube, it is allowed to stand as it is to absorb the analyzed components into absorbing liquid. This sealed tube-burning method has advantages that there is little contamination due to no combustion assistant used and that the quantity of sample is sufficient with trace amount under 1 mg, but it has drawbacks that troublesome operation of sealing tube is required for every sample, that the used sealed tubes should be disposed, thus being uneconomical, that heat-resistant materials such as quartz glass cannot be used virtually due to difficult operation of sealing tube, thereby heating of sealed tube becomes up to 600° C. at most, resulting in impossibility to decompose fire-resistant sample, and the like.
For the hot flask method, three ways of decomposing and absorbing methods are known and these are referred conveniently to as “horizontal-rotating system”, “vertical system” and “horizontal system”.
Thereamong, the “horizontal-rotating method” is described in detail, for example, by W. J. Kirsten in Microchem. J., vol. 7, p. 34 (1963). Procedures are as follows; Namely, a one-sidedly closed quartz tube with a bulge provided near entrance, in which bulge an absorbing liquid is accommodated, is inserted horizontally into a furnace of 850° C. until this side of the absorbing liquid portion to heat, and oxygen is filled up. Then, a quartz bar having the sample thereon is inserted swiftly to close the quartz tube therewith. The closed portion is allowed to rotate downward by 90° together with furnace to decompose the sample. After heated for several minutes, the quartz tube closed with quartz bar is taken out from furnace, cooled, and shaked to absorb the analyzed components into absorbing liquid. This “horizontal-rotating method” has advantages that there is little contamination due to no combustion assistant used and that the quantity of sample is sufficient with trace amount under several mg, but has drawbacks (1) that, since the inner pressure increases due to evaporation of absorbing liquid which is closed in vessel, possibility to cause the leakage is high, (2) that it is dangerous to swiftly insert the quartz bar having organics thereon into the tube heated to 850° C., (3) that, since the tube of which absorbing liquid portion exists nearby furnace is kept heated at 850° C., there is a possibility for absorbing liquid to evaporate up, and (4) that, since the overall furnace is rotated by 90°, a robust material is required.
The “vertical system” is described in detail, for example, by W. J. Kirsten in Microchem. J., vol. 7, p. 34 (1963). Procedures are as follows: Namely, oxygen is filled up in a one-sidedly closed quartz tube installed vertically in a furnace of 850° C. A vessel with the absorbing liquid accommodated therein is inserted swiftly from bottom of quartz tube together with quartz bar having the sample thereon and closed to decompose the sample. Through the diffusion of combustion gas, the testing components are absorbed into absorbing liquid. This “vertical system” has advantage that there is little contamination due to no combustion assistant used and that the quantity of sample is sufficient with trace amount under several mg, but has drawbacks (1) that the memory effect is observed due to residual ash and, since the quartz bar having the sample thereon is not washed with absorbing liquid, it is unsuitable for a sample containing ash, (2) that, since the inner pressure increases due to evaporation of absorbing liquid which is closed leaving accommodate as it is, possibility to cause the leakage is high, and (3) that it is dangerous to swiftly insert the vessel, which accommodates absorbing liquid therein, into the tube heated to 850° C. together with the quartz bar having the sample thereon.
The “horizontal system” is described in detail, for example, by M. E. Fernandopulles et al in Microchem. J., vol. 11, p. 41 (1966). Namely, comparing with “horizontal-rotating system”, modifications are made to raise the temperature of furnace from 1000 to 1050° C. and not to rotate by 90° after closure. This “horizontal system” has advantages that there is little contamination due to no combustion assistant used and that the quantity of sample is sufficient with trace amount under several mg, but has drawbacks (1) that, since the inner pressure increases due to evaporation of absorbing liquid which is closed leaving accommodated as it is, possibility to cause the leakage is high, (2) that it is dangerous to swiftly insert the quartz bar having organics thereon into the tube heated over 1000° C. and (3) that, since the vessel with absorbing liquid portion existing nearby furnace is kept over 1000° C., there is a possibility for absorbing liquid to evaporate up.
As described, the hot flask method has advantages of little contamination due to no combustion assistant used and the quantity of sample sufficient with trace amount under several mg, but has drawbacks due to the existence of absorbing liquid in the vessel on decomposing the sample, and the like.
The vertical type closed tube method is described in detail, for example, by Kikushige Ono, in Summary of Presentations, p. 9 (1996) at Joint Symposium of 63rd Conversazione for Studying Organic Microanalysis of The Japan Society for Analytical Chemistry and 7th Sectional Meeting for Measuring Mass and Force of the Instrumentation and Automatic Control Society. Procedures are as follows: Namely, sample wrapped in combustion assistant is dropped from the top of vertical closed combustion tube heated in furnace, oxygen is blown in from oxygen blowoff port at the upper portion of tube to burn while rotating the sample in the circumferential direction, and combustion gas is passed additionally through filler portion to burn completely. Then, the absorbing liquid is injected from a mechanism for injecting absorbing liquid and all portions including combustion section is washed to absorb the testing components. This vertical type closed tube method has an advantage of less obstruction by ash content etc. because of washing combustion section, too, but has drawbacks that there is a possibility for the washing of filler placed in combustion tube to become insufficient, which remains a memory to contaminate next sample, that the mechanism of washing is complicated, and that the microanalysis is impossible due to contamination from combustion assistant.
As described above, conventional decomposition methods aiming at the analysis of components in organics has their merits and demerits. Moreover, as for the devices automated each method, there have been problems for each method.
The purpose of the invention is, replacing the conventional appliances used for the pretreatment on analyzing the components of halogen and sulfur in a sample which may sometimes contain organics, methods using them and devices automated them, to provide a closed heat-decomposing appliance (hereinafter referred to as “inventive appliance”) for the pretreatment on accurate quantitative analysis or detection of the analyzed components in sample, which requires no combustion assistant, which is not obstructed by ash content present in sample absorbing the analyzed components, which requires no complicated and dangerous procedures, which can be used repeatedly, and which allows to inject the absorbing liquid after heat-decomposition, a pretreatment method (hereinafter referred to as “inventive pretreatment method”) using it, for heat-decomposing the sample which may sometimes contain organics and further dissolving the testing components in sample, a pretreatment device (hereinafter referred to as “inventive pretreatment device”) automates it, further a method (hereinafter referred to as “inventive analytical method”) for analyzing the testing components after pretreatment, and a device (hereinafter referred to as “inventive analytical device”) therefor.